The phytoplankton values here are derived from measurements near Kingston-Rhinecliff, New York, and do not take into account spatial variation in biomass and parameters in the freshwater river as a whole, and thus, are not identical to estimates in other papers (see Caraco et al., 1997; 2000). The values of GPP, Ra and NPP for the phytoplankton are explained in the text.

(1) Values for macrophytes from Cole and Caraco, 2001; Caraco et al., 2000; Harley and Findlay 1994. We assumed that the values for daily macrophyte net production in Caraco et al., 2000 apply to a 100-d season; we cannot estimate macrophyte gross production or respiration from this approach.

(2) Periphyton values are approximate and based on biomass data in Bianchi et al., 1993 assuming the same biomass-based photosynthesis as phytoplankton. This is likely an overestimate.

(3) Watershed inputs are based on Howarth et al., 1996.

(4,5,6) These values come from averages from several sources (Findlay et al., 1998; Roland and Cole, 1999; Caraco et al., 2000; Cole and Caraco, 2001), and are explained in those sources. Values should be considered approximate only.

(7) This is the difference of GPP and R in this table.

(8) Net advective outputs are estimated as difference between all inputs (GPP + watershed inputs) - R. In some cases we were able to estimate values both prior to the zebra mussel invasion and following it; where we did not have a separate estimate for both periods we used the existingvalue for both periods.

In the years prior to the zebra mussel invasion, annual NDPZP for the mid Hudson region averaged 243 ± 40 g C m-2 y-1, among years (with 95 percent CI) a value close to that reported by Malone (1977) for New York Harbor and measured recently at the Verrazano Narrows by Taylor et al. (G. Taylor, personal communication). (Fig. 9.9B). In comparison to other rivers primary production in the tidal-freshwater Hudson was moderately high. Following the zebra mussel invasion (1993-2000) NDPZP for the mid Hudson region averaged 61 ± 8.3gC m-2 y-1, which groups the Hudson during this period with systems with the lowest reported planktonic primary production for rivers and estuaries in general.

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